OFFSET
1,6
MATHEMATICA
a[n_] := Module[{p = Product[Prime[i], {i, 1, n}], j = 0}, While[!PrimeQ[p * 3^j + 1], j++]; j]; Array[a, 100] (* Amiram Eldar, Sep 11 2021 *)
Module[{j=0}, While[!PrimeQ[# 3^j+1], j++]; j]&/@FoldList[ Times, Prime[ Range[60]]] (* Harvey P. Dale, Jan 03 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Sep 04 2005
STATUS
approved